Hi @Lili22, sorry to hear about what has happened. 
Your question has been translated to English as this is an International forum, please post any replies in English and it will be easier for me and other users to assist you.
If this occurred directly after the device was dropped and it worked fine before, there are some damages caused by the fall that is the cause of this and since this is a hardware defect, the device will need to be examined by a trained technician at an authorized service centre.
Your Local support team will assist you further with having the device sent in, so get in touch with them.
I hope that helps!
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